Ask HN: What short and effective exercises do you recommend?

I am convinced that I should exercise regularly, but I prefer short and effective exercises which will get me to 80% energy with 20% effort so to say. My intention is not to be Hercules, but to be healthy enough to think clearly and be active. Types of exercises I follow and recommend: [1] 5 Stretches Day9 recommends before playing Starcraft 2: https://www.youtube.com/watch?v=SSbf4mBKq-o [2] Exercise to improve hunchback posture forward head carriage correction: https://www.youtube.com/watch?v=LT_dFRnmdGs [3] Skipping for 5 mins. How to Jump Rope for Boxing: https://www.youtube.com/watch?v=GRStB06uhgE [4] Sleeping for 7 hours.